Removal of ketone impurities in the preparation of butadiene-1,3



March 20, 1956 P. MOKQREILLY ETAL 2,739,176 I v REMOVAL OF KETONEIMPURITIES IN THE PREPARATION OF BUTADIENE-1,3 Filed Aug. 22, 19

INVENTORS PARK MKNIGHTRE/LL Y JOHN [DOA/P DOUGLAS (REWARD/NE 7 CHARLESM/LA/E F/IVIGA N Y Bow AEM'M r ATTORA/ Y8 -2,739,176 'R'EMovA-Lorixn'ronnnurunrrtss in Tris runrxnarronor BUTXDlE-NE-itfi Park McKnightReilly, John Edgar Douglas Carwardine, and Charles Milne Finigan,Sarnia, Ontario, Canada, assignors to Polymer Corporation Limited,Sarnia, Gin tario, Canada, a corporation of Canada Application August22, 1952, Serial No. 305,886 Claims priority, application Canada August14, N52

3 Claims. (Cl. 260-56815 This invention relates to theremoval of ketoneimpurities in the preparation of butadiene-1,3.

More particularly, the invention is concerned with such removal duringthe known process for the preparation of butadiene-1,3 which comprisesthe steps of dehydrogenating, utilising a calcium-nickel phosphatecatalyst, a hydrocarbon mixture containing a substantial quantity of C4hydrocarbon of greater saturation than butadiene-1,3, e. g. normalbutylene; fractionating the reaction products to isolate the C4fraction; and extracting butadiene-1,3 from extracts the butadiene-1,3and any acetylenes from the C4 fraction.

Copending application Serial No. 285,832 by Cotton et al., filed May 2,1952, describes the removal of acetylenes so that they do notcontaminate either the copper ammonium acetate or the butadiene product.This is effected by performing the extraction in two steps, firstlycontacting the C4 fraction with a relatively small amount of the copperammonium acetate whereby the more soluble acetylenes are removed, andsecondly contacting the substantially acetylene-free C4 fraction with arelatively large amount of the copper ammonium acetate to extract thebutadiene.

In this specification, the calcium-nickel phosphate catalyst is thepromoted catalyst described broadly in Dow Chemical Companys UnitedStates Patent No. 2,442,320. The copper ammonium acetate solvent is, asis well known, mainly composed of cuprous ammonium acetate but alsocontains at least a small amount of cupric ammonium acetate.

In the above known process using the calcium-nickel I tion with copperammonium acetate, at least most of the ketones formed during thedehydrogenation reaction. The most convenient method of removing theketones is by means of extraction with water and this is preferablyeffected prior to the fractionation step, though it may be efiectedafter the fractionation step.

The present invention, quite apart from improving the dissolution of thebutadiene in the copper ammonium ac etate, reduces ketone impurities inthe butadiene finally extracted and provides a useful method ofobtaining ketones as a by-product. The yield of ketones may be im- Unitfi ms ,1

,. Mar. 20 1956 proved by introducingadditional acetiylenes so as to bepresent during the dehydrogenation reaction. Such additional acetyle'nesmay be recycled from thenlater acetylene extraction stage describedabove in connection with copending application Serial .No. 235,832.

The invention is illustrated in the accompanying drawing which shows aflow diagram of a ketone removal circuit adapting a washing tower, orso-called quench "r connected-topipe 8 *by 'aapump 12 and a, pipe .13. Apipe 14 carries steam into tower 10 to strip ketones from the water, theketones leaving tower by a pipe 15. A pipe 16 fitted with a valve 17connects pipe 13 to waste.

In the preparation of butadiene-1,3 a gaseous mixture of hydrocarbonsis'dehydrogenated in a reactor containing a calcium-nickel phosphatecatalyst and maintained at a temperature of 1000- 1200 F. The effluentgaseous reaction product may contain about 0.8% by weight of ketonesformed during the reaction. These gases are passed through coolers untiltheir temperature is in the region of 160 F. and are then passed intothe tower 1 via the inlet pipe 3. The gases pass up the tower 1 throughthe layers 2 of packing and are washed by water I entering the top ofthe tower 1 from the pipe 8. The

water removes most of the ketones in the gases and the substantiallyketone-free gases leave the tower 1 via the outlet pipe 4 whence theyproceed to fractionation and extraction with copper ammonium acetate aspreviously described. The tower 1 efiects a cooling of the gases toabout 80 F.

A portion ofthe water collecting at the bottom of tower 1 and containingextracted ketones is removed via pipe 5 and pump 6 to the strippingtower 10 where the ketones are extracted and removed via outlet pipe 15.The substantially ketone-free water is returned from the botttom of thetower 10 to the tower 1 via pipe 11, pump 12 and pipes 13 and 8.

A quantity of Water vapour is present in the dehydrogenation reactionproducts and much of this will condense in the tower 1 so that thequantity of water circulating will continuously tend to increase. It isthus necessary to remove water either continuously or at intervals viathe branch pipe 16 and valve 17. The valve 17 may be controlledautomatically in accordance with the level of water in the bottom oftower 1.

The quantity of water required to be circulated through the tower 10will depend on the particular circumstances of each case andparticularly on the quantity of ketones contained in the gases. With anormal rate of flow of the gases, 30,000 lb. of water per hour has beenfound satisfactory.

Where it is possible to dispose of waste water containing ketones andWhere the ketones are not required to be recovered, the fractionationvessel may be dispensed with, fresh water passed into the top of thetower 1 and, ketonecontaining water discharged to waste. A recirculationcircuit may still be used and in this case, ketone-containing water maybe removed through a valve from time to time or by a continuous bleed.

We claim:

1. A process for the preparation of butadiene-1,3 com-' cfiiuent'of thedehydrogenation reaction with water to extract substantially all of theketones formed during the.

dehydrogenation reaction, fractionating the washed efiiuent to isolatethe C4 fraction,"-and extracting butadiene-1,3 from the C4 fraction withcopper ammonium acetate.

2. A process for the preparation of butadiene-l,3 comprisingdehydrogenating at elevated temperature an n-butylene-rich gaseoushydrocarbon mixture utilizing a calcium-nickel phosphate catalystwhereby substantial quantities of butadiene-1,3 are formed, washing thegas- 7 eous eifiuent of the dehydrogenation reaction in awashbutylene-rich gaseous hydrocarbon mixture utilizing a calcium-nickelphosphate catalyst whereby substantial quantities of butadiene-1,3areformed, washing the gaseous eifiuent of the dehydrogenation reactionwith substantially alkali-free water to extract substantially all of theketones formed during the dehydrogenation reaction, fractionating thewashed efiluent to isolate the C4 fraction, and extracting butadiene-1,3from the C4 fraction with copper ammonium acetate.

References Cited in the file of this patent UNITED STATES PATENTSQuerforth Oct. 3, I933 Ipatieif et al Aug. 19, 1941 Asbury et al June11, 1946 McCombie Apr. 1, 1947 Britton et al. May 25, 1948 Murphree Oct.12, 1948 Engel Sept. 26, 1950

1. A PROCESS FOR THE PREPARATION OF BUTADIENE-1,3 COMPRISINGDEHYDROGENATING AT ELEVATED TEMPERATURE AN NBUTYLENE-RICH GASEOUSHYDROCARBON MIXTURE UTILIZING A CALCIUM-NICKEL PHOSPHATE CATALYSTWHEREBY SUBSTANTIAL QUANTITIES OF BUTADIENE-1,3 ARE FORMED, WASHING THEGASEOUS EFFLUENT OF THE DEHYDROGENATION REACTION WITH WATER TO EXTRACTSUBSTANTIALLY ALL OF THE KETONES FORMED DURING THE DEHYDROGENATIONREACTION, FRACTIONATING THE WASHED EFFLUENT TO ISOLATE THE C4 FRACTION,AND EXTRACTING BUTADIENE-1,3 FROM THE C4 FRACTION WITH COPPER AMMONIUMACETATE.